Machine for finishing pistons



Nov. 7, 1950 w. M. VENNER ETAL 2,529,433

MACHINE FOR FINISHING PISTONS Filed Jan. 2, 1947 INVENTORSZ WILLIAM M. VENNER PERCY L BOWSER JR.

ATTORNEYS.

Patented Nov. 7, 1 950 MACHINE FOR FINISHING PISTONS William M. Venner, Clayton,- and Percy L. Bowser, Jr., University City, Mo.

Application January 2, 1947, Serial No. 719,843

3 Claims.

This invention relates to a machine for finishing pistons, and, more particularly, pistons of the trunk-type, whose particular application is for use in internal combustion engines. In such a piston, comprisin a head and a skirt, the head is finished, usually by grinding to a diameter somewhat smaller than that of the engine cylinder. The skirt may also have a varied contour, namely, it may be oval or elliptical, but, in some cases, it is ground cylindrical. The skirt also usually has a taper and this is also true of the head. The piston may be supported in a manner to obviate the use of centers, so as to be, in fact, a centerless grinder.

One of the objects of this invention is to provide a machine whereby the finishing of a piston may be accomplished in an efficient and economical manner.

Further objects will appear from the detail description in which will be set forth an illustrative embodiment of this invention; it is to be understood, however, that this invention is susceptible of various embodiments within the scope of the appended claims.

In accordance with an illustrative embodiment of this invention, the piston finishing means has a movable support which is adapted to present a piston to the finishing means, such as a grinder. This support has-a surface" corresponding to the desired surface of the piston, and mechanism is provided adapted to drive the support and the piston in synchronism. Means may be provided for adjusting the support and for adjustably positioning the piston on the support in order to adapt the machine for various size pistons. The connection of the driving mechanism to the piston may be flexible for permitting ready removal of the piston. Where the piston has a cylindrical surface the support for presenting the piston to the finishing means may be cylindrical; if, however, it is desired that the piston have an elliptical or cam surface, then the support has a cam surface, but in reverse to the desired cam sur-* face of the piston.

In the accompanying drawing:

Figure 1 is a section along the line ll of Figure 2;

Figure 2 is a section of the line 2--2 of Figure 1, parts being shown in elevation; and

Figure 3 is a detail of Figure 2.

Referring now to the accompanying drawing, 1 designates a piston having a head 2, provided with ring grooves, having a skirt 3 which may be partially separated from the head by circumferential slot 4, and having Wrist 'pin bosses adapted to receive a wrist pin 6. The diameter of the head is usually smaller than the diameter of the skirt, and theskirt may be cylindrical or cam ground, as previously described.

Mounted in a frame ll] is'the mechanism for presenting a piston to a finishing element, such as a grinding wheel II. It comprises a support in the form of a roller l2, adapted to be keyed to a shaft 13 supported in bearings I 4. These bearings [4 are supported through eccentrics l5 in the side members l6 of the frame, and each of the eccentrics is provided with an adjusting head I! adapted to be fixed by set screw [8, whereby the support may be adjusted up and down with respect to the grinding wheel I I. The support I2 is provided with asurface corresponding to the desired surface of the piston, and where the piston is to be cam groundthis'surface is the reverse of the desired cam on the piston.

Mounted on a shaft 20, also supported in side members It by eccentrics 2|, is a roller 22 which, in this case, may be loose on the shaft. The eccentrics also have heads 23 and clamping screws 24. The roller 22 gauges and positions the piston laterally and may be adjusted for various size pistons. I

Pivoted on a shaft 30 is a lever 3| provided with a roller 32 adapted to engage to piston above its center. Interposed between the lower end of a bracket 33 and the lower end of the lever, is a spring 34 on a stud 35 passing loosely through the bracket and provided with a head 36. The lever, as a whole, is forked to take over the bracket, and has a stop 31 engaging the bracket. The lever 3| can be swung out at its upper end to allow the insertion of the piston and when released will cause the spring 34 to hold the piston above its center as it is supported by the support I2 and the roller 22.

The wrist pin of the piston has taking thereover a forked head provided with plunger 4| (Figure 3) engaged by spring 42, so that when the fork is snapped over the pin the piston will be retained in the fork, the plunger :passing beyond the center of the pin to hold the piston in position. The fork is on the end of a shank 43 provided with a square or angular opening 44 in which fits an angular extension 45 of a shank 46. The ends of the shanks 43 and 46 are reversely threaded to receive a sleeve 4'! held by clamping nut 48. By this manner the length of the shank structure 43-46 may be adjusted by manipulation of the sleeve 41. The shank 46 is pivoted by pin as in a sleeve 50, which, in turn,

is pivoted by a pin 5| in a shaft 52, so as to provide a universal joint between shank 46 and shaft 52. This shaft 52 is supported in a bearing '53 and has fixed thereto a gear 54 meshing with gear 55, fixed to a shaft 56, supported in bearings 51 and 58. The lower end of the shaft has fixed thereto a gear 59 meshing with a gear 60, fixed to a shaft 6|, supported in the bearing 62, and driven by a motor 63. The shaft 6| may be connected to the shaft l3 by suitable gearing, such as a silent chain 64 passing over wheels 65 and 66. By the mechanism described, and by the interconnection of the shaft [3 of the support and the shank 43 attached to the piston, the support l2 and the piston are driven in synchronism.

The operation of the mechanism is as follows: Assuming that the contour of the piston has been determined and that the support I2 has been formed to correspond with the desired contour of the piston; and in the case where the piston is to be cam ground, the support has been provided with a surface which is the reverse of that of the piston; the support is placed in position in its bearings where it will present the proper face to the piston. The support'will be adjusted to the size of the piston and the roller 22 will also be adjusted to that size. The piston will then be positioned along the support and the roller 22 by the adjustment 4'! described. The piston will now be held on and against the support I2 and the roller 22 by the roller 32. Finishing may then be proceeded with, starting the motor which then drives the support l2 and the piston in synchronism, so as to form the desired surface on the piston, whether cylindrical or cam ground. After the piston has been finished, the frame can be moved out of position, so as to clear the grinding wheel; this frame, as usual, being fed laterally of the grinding wheel. When the piston is free of the grinding wheel the shank 43 can be swung on its universal joint, so as to permit removal of the piston therefrom. The support l2 may be readily removed by slipping the shaft l3 endwise, the latter being keyed to the support.

Having thus described the invention, what is claimed anddesired to be secured by Letters Patent is:

1. A piston finishing machine, comprising, finishing means, a frame member movable relatively to said finishing means, a rotary support journaled on said frame member at a fixed distance from said finishing means, said support having a cross-sectional shape complementary to that to which the piston is to be finished, driving means connectible with the piston to rotate the same and axially adjustable to position the piston on said support, and means for rotating said support in constant relation to the rotation of said driving means.

2. A piston finishing machine, comprising, finishing means, a frame member movable relatively to said finishing means, a rotary support journaled on said frame member at a fixed distance from said finishing means, said support having a cross-sectional shape complementary to that to Which the piston is to be finished, driving means connectible with the piston to rotate the same, means for rotating said support in constantrelation to the rotation of said driving means, and means for adjusting said driving means axially without disturbing said relation.

3. A piston finishing machine, comprising, finishing means, a frame member movable relatively to said finishing means, a rotary support journaled on said frame member at a fixed distance from said finishing means, said support having a cross-sectional shape complementary to that to which the piston is to be finished, axially adjustable driving means having a snap-on connection with the piston pin, means for rotating said support in constant relation to the rotation of said driving means, and means for adjusting said driving means axially without disturbing said relation.

WILLIAM M. V'ENNER. PERCY L. BOWSER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,000,586 Foerster et al. May 7, 1935 2,024,283 Gertiser Dec. 1'7, 1935 2,045,894 Binns June 30, 1936 

